1. Field of the Invention
The present invention relates to an electrical contact, and particular to an electrical contact of a Land Grid Array (LGA) socket connector for securing a true electrical connection between a central process unit (CPU) and a printed circuit board (PCB).
2. Description of Related Art
In general, a LGA socket connector is used to connect a CPU to a PCB. Typically, the LGA socket connector includes an insulative housing and a plurality of electrical contacts received in the insulative housing. For example, U.S. Pat. Nos. 5,092,783, 5,746,626, 6,146,152, 6,217,342, and 6,257,899 disclose an LGA socket connector with a plurality of electrical contacts received therein. Each of the electrical contacts comprises a top curved contacting portion extending beyond an upper surface of the LGA socket connector and a bottom curved contacting portion extending beyond a lower surface of the LGA socket connector. When a CPU and a PCB are assembled to the socket connector, the top and bottom contacting portions are pressed inwardly into the insulative housing and establish an electrical connection between the CPU and the LGA socket connector.
Further referring to FIGS. 3-5 of U.S. Pat. No. 6,217,342, an electrical contact (14) comprising an arcuate convex spring (36) with a pair of opposite spring arms (44) and a pair of opposite noses (38) at ends of the spring (36), and a pair of retention legs (40) extending inwardly from the noses (38). When circuit members (46, 48) move toward each other, the noses (38) are pressed inwardly. The spring arms (44) move inwardly and sideward, thus, a mating force between the electrical contact (14) and the circuit members (46, 48) includes a vertical component force and a horizontal component force. As the circuit members (46, 48) move further toward each other, the vertical component force and the horizontal component force both increase. However, the horizontal component force is larger and increases faster than the vertical component force. In general, the vertical component force is not enough to secure a true electrical connection between the noses (38) and the circuit members (46, 48). While there is a large vibration, an electrical connection between the contact and the circuit members (46, 48) may be temporally interrupted. In addition, as the horizontal component force varies fast and a varied force may be larger than a frictional force between the nose (38) and pads (50, 52) of the circuit members (46, 48). Therefore, even a slight vibration may produce a horizontal scrubbed movement between the pads (50, 52) and the nose (38), and such affects the electrical connection between the electrical contact (14) and the circuit members (46, 48).
Hence, an electrical contact capable of providing a true electrical connection between external circuit members is desired.
Accordingly, an object of the present invention is to provide electrical contacts for an LGA socket connector which is capable of providing a true electrical connection between a CPU and a PCB.
In order to achieve the object set forth, an electrical contact received in a socket connector for connecting a CPU to a PCB includes a retention plate, a spring arm and a connecting arm connecting the spring arm to the retention plate. The retention plate engages with the socket connector for securely retaining the electrical contact in the socket connector. The spring arm includes a first curved arm bent from the connecting arm toward the retention plate, a second curved arm bent from the first spring arm opposite to the retention plate and a third curved arm bent from the second spring arm toward the retention plate. The first curved arm has a bottom contacting end for contacting with the PCB. Similarly, the third curved arm has a top contacting end for contacting with the CPU. While the socket connector is fully sandwiched between the CPU and the PCB, the first spring arm and the second spring arm deform opposite to each other whereby the top and bottom contacting ends move in a substantially vertical direction. Such establishes a true electrical connection between the CPU and the PCB.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the preferred embodiment when taken in conjunction with the accompanying drawings.